Thermal storage and transport

ABSTRACT

The carrying case for storing and transporting heated articles includes a thermal storage assembly having a heat retention member for absorbing and retaining sensible heat and for releasing the sensible heat of a extended period time. The thermal storage assembly includes a heating coil assembly secured to a surface of the heat retention member. The heating coil assembly includes a resistive heating coil disposed adjacent to the heat retention member. The heating coil has a power cord connected to the coil with the coil being retained within a sealed thermally conductive pouch.

I. BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to an apparatus for storing and transportingheated articles to provide a delayed discharge of heat to the articleduring transportation or storage. More particularly, this inventionpertains to an apparatus for retaining a level of heat in a food productbeing transported or stored.

2. Description of the Prior Art

Food products (such as pizza) are frequently prepared and cooked at astore location. The prepared products are then delivered to a customerat a home or place of business.

A heated food product may be stored at the store location awaiting adelivery person's transportation of the food product to the customer.During both the storage and the transportation, the product may lose itssensible heat.

In the event of heat loss, a product may become unacceptable to aconsumer. As a result, effort is made to retain the heat of the productafter its cooking preparation.

In pizza delivery, it is common to prepare a pizza and store it inindividual cardboard boxes. The cardboard boxes are then placed underheat lamps awaiting pickup by a delivery person. The delivery personthen stores the cardboard containers in a thermally insulated carryingcase for delivery to the home owner.

The use of heat lamps for providing additional heat during storage andthe use of thermally insulated carrying cases have improved the heatlevel of the product finally delivered to the consumer. However, it isstill desirable to find a means for enhancing the heat level of thefinal product delivered to the consumer.

II. SUMMARY OF THE INVENTION

According to a preferred embodiment to the present invention, atransport device is disclosed including a container having an interiorvolume for receiving a heated product. Disposed within the container isa heat transfer article having a thermal mass exposed in heat transferrelation to an electrically resistive coil. A power cord connects thecoil to a source of electrical energy.

III. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a thermal storage and transport deviceaccording to the present invention shown in an embodiment adapted forpizza delivery and shown used in one mode of use;

FIG. 2 is the view of FIG. 1 illustrating an alternate mode of use;

FIG. 3 is a cross-sectional longitudinal view of the device of FIG. 1;

FIG. 4 is a cross-sectional longitudinal view of a novel thermal packassembly for use in the device of FIG. 1; and

FIG. 5 is an exploded perspective view of the thermal pack assembly ofFIG. 4.

IV. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to the various figures in which identical elementsare identically numbered throughout, a description of the preferredembodiment of the present invention will now be provided. The presentinvention will be described with reference to a container for storingand transporting heated food articles. In particular, the presentinvention will be described with reference to a pouch for storing andtransporting pizza which is cooked and placed in individual cardboardboxes as is customary. While the invention is being disclosed in apreferred embodiment, it will be appreciated that the invention can beused in a wide variety of applications for storing or transportingheated articles where it is desired to maintain the heated articles atan elevated temperature relative to ambient temperature.

With reference to FIGS. 1-3, a carrying pouch or case 10 is shown havinga top wall 11, bottom wall 12, side walls 13, 14, rear wall 15, andfront flap or cover 16. The walls 11-15 and flap 16 are formed of soft,pliable fabric layers 19 with thermal insulation 21 contained betweenthe layers 19.

The flap 16 opens to expose a pouch interior 17. The pouch interior 17is sized to receive a plurality of cardboard boxes each containingindividual pizzas with the cardboard boxes stacked on top of oneanother. It will be appreciated that pouches 10 thus described forcontaining pizzas and formed of insulative lining form no part of thisinvention per se and are well known in the prior art. The rear wall 15includes vent holes (not shown) for venting moisture from the interior17.

The improved pouch 10 includes novel features for enhancing the thermalretention capabilities of the pouch 10 and for carrying. Side walls 13,14 and rear wall 15 are formed in two insulated segments (such assegments 15a, 15b in FIG. 3) separated by a stitch line 23. Line 23 runslongitudinally along the midpoint of the height of walls 13-15 to permitthe height of pouch 10 to be collapsed. Flap 16 is flexible along itslength and is hinged to bottom wall 12 at a stitch line 25. Forcarrying, the pouch 10 includes an elongated strap 27 terminating atboth ends at an inverted V-shaped strap 29. Strap 27 is secured to theapex of the V-shaped strap 29. The V-shaped straps 29 are positionedopposite both sidewalls 13, 14 (although only strap 29 opposite sidewall14 is shown in FIG. 1). For weight distribution, the ends of V-shapedstraps 29 are positioned on opposite sides of the mid-points of sidewalls 13, 14. The straps 29 are joined by strap segments 29a runningparallel along the underside of bottom wall 12 (FIG. 3) and stitched towall 12 such that the load on strap 27 is divided along V-shaped straps29 and distributed along the bottom wall 12. Strap 27 is sized to fitaround the neck of a delivery person 10a with rear wall 15 facing andabutting the waist of the delivery person 10a (FIG. 1).

Pouch 10 also includes a hand strap 31 shown in use in FIG. 2. Strap 31includes a transverse strap 33 stitched to the intersection of sidewalls13, 14 and top wall 11. Strap 31 also includes a longitudinal strap 35stitched to the midpoint of strap 33 and to the midpoint of theintersection of rear wall 15 and top wall 11.

It will be noted that the flap 16 includes an area 37 of a hook and loopfastener (sold under the trademark Velcro) on the inner surface of flap16 from its leading end 16a to a termination line 16b adjacent hinge 25.The Velcro fastener 37 secures to a mating Velcro fastener 39 disposedon a forward end of the upper wall 11. Accordingly, flap 16 may befolded over from an open position (shown in FIGS. 1 and 3) to a closedposition (FIG. 2) with the Velcro fasteners 37, 39 secured to oneanother in order to secure the flap 16 in a closed position. Since area37 is larger than Velcro strip 39, the flap 16 can be secured to strip39 at any one of a number of closed positions. For example, FIG. 2 showsflap 16 secured to top wall 11 in one position (illustrated by theposition of leading end 16a in solid lines). The phantom line 16a showsflap 16 extended over top wall 11 to partially cover top wall 11 toaccommodate a smaller number of articles within pouch 10.

The wide walls 13, 14 include triangular gusset flaps 13a, 14a, whichvary from a maximum thickness at the leading end 11a of the upper wall11 to a minimum thickness at leading end 16a of the flap 16. The sideflaps 13a, 14a include folds 23a such that as the flap 16 is moved tothe closed position, the folds 23a cause the flaps 13a, 14a to foldinwardly and cover side openings to the interior 17 (as illustrated inFIG. 2). The side flap 14a is secured to flap 16 by a Velcro fastener 45for reasons that will become apparent. Accordingly, when the flap 16 ismoved to the closed position, the side flaps 13a, 14a cover the openingsand prevent air from passing from the interior 17 out of the pouch 10.This is an enhancement over prior art pouches 10 which did not includesuch flaps. In the prior art, when the forward flap was moved to aclosed position, opposing surfaces of the forward flap and the sidewalls of the prior art pouches defined a large opening for air to flowfrom the interior of the pouch to the exterior of the pouch.

The bottom wall 12 includes a cover 12a disposed within the interior 17.The cover 12a is disposed in parallel overlying relation to the interiorof the bottom wall 12. Cover 12 extends beyond hinge 25 (as illustratedin FIG. 3) and terminates at a Velcro strap 41 for sealing attachment toarea 37.

The cover 12a defines a separate interior volume (or sub-chamber) 43which is accessible through an opening at a leading end of the cover12a. Chamber 43 is sized to receive a thermal pack assembly 20. Thethermal pack assembly 20 includes a rigid base 100 which is preferablyformed of wood or other non-thermally conductive materiel with the base100 sized to be received within the chamber 43 and substantially fillthe chamber 43 with the base 100 being parallel to cover 12a. Thethermal pack assembly 20 further includes a thermally insulating foamcushion 102 disposed on an upper surface of the base 100 with the foamcushion 102 substantially covering base 100 and secured thereto throughany suitable means such as adhesive or the like. An upper surface of thefoam cushion 102 is provided with a foil cover 104 which is a thermallyconductive metal foil completely covering the upper surface of the foamcushion 102.

As shown in FIG. 5, a heating coil subassembly 103 includes anelectrically resistive heating coil 105 disposed in a generallyrectangular plane. The heating coil 105 is sandwiched between twothermally conductive metal foils 106, 108. The foils 106, 108 are sealedby metallic tape 110 (not shown in FIG. 4) so that liquid such as wateror other undesirable elements cannot be admitted into contact with thecoil 105. Aluminum tape 112 secures the subassembly 103 to the foillayer 104 and base 100.

The subassembly 103 includes a power cord 114 having a neutral and anenergized conductor 114a, 114b. The neutral conductor 114a is connectedto one end of the coil 105. The energized conductor 114b is connected toan opposite end of the coil 105. The energized conductor 114b includesfirst and second thermostats 116, 118 connected in series with the coil105. The cord 114 terminates at a conventional wall outlet plug 120 suchthat the coil 105 can be connected to an AC source of electrical powersimply by inserting the plug 120 within a wall outlet. A plastic clip122 secures the cord 114 to base 100.

The subassembly 103 is secured to the underside of a thermal retentionpouch 200. The pouch 200 is secured to subassembly 103 and base 100 bymetallic tape 112.

The thermal retention pouch 200 is a completely sealed envelope ofplastic in which is contained an open cell foam pad 202. The foam pad isimpregnated with water 204 contained within the pouch 200. The pouch 200is partially evacuated during formation. As a result of this assembly,when the coil 105 is energized and distributes heat, the heat is passedinto the pouch 200 and the water temperature within the pouch 200 iselevated. The water 204 retains the heat to later slowly release theheat over time as sensible energy when the cord 114 is disconnected froma power source. It will be appreciated that a pouch 200 thus describedforms no part of this invention per se. An example of such is shown incommonly assigned U.S. Pat. Nos. 5,357,693 and 5,500,010.

Having thus generally described the structure of the present invention,it will be noted that the pouch 200 and resistive heating element 105have substantially equal surface areas such that the resistive heatingelement 105 produces heat along the entire undersurface of the pouch200. The upper foil 106 distributes heat evenly from the coil 105 to theundersurface of the pouch 200 to prevent localized overheating.Overheating is also avoided through thermostats 116, 118. The firstthermostat 116 is selected to open at 1000° C. ±5° C. The secondthermostat 118 is selected to open at 105° C. ±5° C. Accordingly, thesecond thermostat 118 acts as a safety override in the event of failureof the first thermostat 116. The coil 105 is shown in serpentinegeometry. The coil 105 preferably has a length of about 18 feet with aresistance of about 5.6 ohms per foot.

In addition to transmitting heat to the pouch 200, the coil 105transmits heat to the bottom foil 104 covering foam 102. Accordingly,when the plug 120 is inserted within a wall outlet, the coil 105 beginsheating. Heat from the coil 105 is distributed to both the pouch 200 andto the foil 104.

The thermal pack assembly 20 includes its various elements being sizedsuch that the surface area of the pouch 200 and coil 105 are smallerthan the surface area of the foam pad 102 and base 100. While the pouch200 and coil 105 have a width approximately equal to the width of thefoam pad 102, their length is substantially smaller than the foam pad102. The pouch 200 and electrical grid 105 are positioned in overlyingrelation to the foam pad 102 at a leading end 102a to provide an area220 of pad 102 and foil 104 towards the trailing end 102b of the foampad 102 which is not covered by the pouch 200 and the coil 105.Accordingly, during periods of time when either the coil 105 is beingheated or the pouch 200 is releasing heat, the leading end 20a of thethermal pack assembly 20 will be hotter than the trailing end 20b.

As shown in FIG. 3, the thermal pack assembly 20 is placed within thechamber 43 with the trailing end 20b of the thermal pack assembly 20positioned toward the rear wall 15 of the pouch 10. As a result, thegreatest source of sensible heat is at the forward end 20a of thethermal pack 20 adjacent the flap 1G. This is done recognizing that thegreatest heat loss is through the forward end of the pouch 10 due to thepresence of the flap 16. The combination of placing the thermal pack 20near the front end of the flap 1G and providing the flap 16 with sideflaps 13a, 14a provides the greatest amount of heat at the forward endplus enhances the structure of the pouch 10 to retain heat at theforward end.

The foil 104 covering the foam pad 102 transmits heat from the front end20a of the assembly 20 towards the rear end 20b of the assembly 20.Accordingly, heat can radiate off of the foil 104 at the area 220 of therear end of the assembly 20 to heat articles within chamber 17positioned above the trailing end 20b of the assembly 20. The cord 114is secured to plastic strap 122 (FIG. 5) to provide a strain relief suchthat a worker pulling on the cord 114 cannot dislodge the cord 114 fromthe grid 105.

With the structure thus described, the apparatus can be used in a pizzashop by inserting the plug 120 within a wall outlet. This energizes thecoil 105 to transmit heat to the pouch 200 and thereby store heat withinthe pouch 200. Furthermore, the heat from the coil 105 is distributed tothe interior 17 of the pouch 10 along the length and width of foil 104.As a result, pizza can be formed, cooked and placed in individualcardboard boxes as is conventional. The filled cardboard boxes can thenbe placed within the chamber 17 awaiting pickup by a delivery personwithout the need for application of additional energy through externalheating lamps as was required in the prior art.

When a delivery person desires to deliver the pizzas, he simply unplugsthe cord 114 from the outlet and transports the entire pouch 10containing the pizza packages. After the cord 114 is unplugged,additional energy is not being provided to the coil 105. Instead, thepouch 10 is releasing its stored energy to retain the pizza at a desiredelevated temperature throughout transportation. During the storagephase, the flap 16 can be closed since the cord 114 may be passedbetween the Velcro fasteners 37, 41 of the side wall flap 14a. As aresult, the flaps 13a, 14a retain as much heat as possible within theinterior 17.

Various enhancements can be made to the present invention to improve itsoperation. For example, fluid may be lost through the walls of theplastic of the pouch 200 through time. Vapor can simply pass through themicropores of the plastic wall. To avoid such loss of fluid, metal canbe vacuum deposited on the plastic to further seal the plastic andprevent vapor loss through the plastic. This improves the duration andlife of the pouch 200. The bottom foam layer 102 provides thermalinsulation to the base 100 to ensure that as much heat as possible risesupwardly into the chamber 17 to heat the pizza. The bottom board or base100 is rigid to improve the carrying capability of the pouch for adelivery person.

While the preferred embodiment illustrates the use of water 204 withinthe pouch 200 as is conventional, the heat sink could be a dielectricoil such as mineral oil or the like. Such oils are not electricallyconductive. Further, such oils have higher vapor pressures and can beheated to higher temperatures without risk of bursting of the pouch 200.Such oils do not corrode metals and are non-toxic. Also, a phase changematerial can be used in pouch 200 to store energy as the latent heat ofthe phase change.

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

What is claimed is:
 1. A thermal storage assembly comprising:a heatretention member for absorbing and retaining sensible heat and forreleasing sensible heat over extended periods of time; a heating coilassembly secured to a surface of said heat retention member, saidheating coil assembly including a resistive heating coil disposed overan area substantially equal to an area of said heat retention member,said coil disposed within a sealed thermally conductive pouch; a powercord extending into said thermally conductive pouch with an internal endof said cord secured to said coil, an external end of said cord havingmeans for releasable connection to a source of electric power; a rigidbase having a surface area greater than an area of said heating coilassembly; said heating coil assembly and heat retention member securedto said base with said coil assembly disposed between said base and saidheat retention member, said coil assembly and heat retention membercovering only a portion of said base to define an uncovered portion ofsaid base; and a thermally conductive material extending from a locationadjacent said heating coil assembly to cover said uncovered portion forconducting heat from said heating coil assembly throughout saiduncovered portion.
 2. A thermal storage assembly according to claim 1further comprising a thermally insulating foam disposed between saidbase and said thermally conductive material.
 3. A thermal storageassembly according to claim 1 wherein said thermally conductive materialis a metallic foil.
 4. A thermal storage assembly according to claim 1,wherein the heat retention member comprises water.
 5. A thermal storageassembly according to claim 1, wherein the heat retention membercomprises a dielectric oil.
 6. A thermal storage assembly according toclaim 1, wherein the heat retention member comprises a phase changematerial for storage of latent heat.
 7. An apparatus for storing aheated article, said apparatus comprising:a case having walls definingan interior volume sized to receive said article, said walls furtherdefining an opening for access to said volume; a cover for closing saidopening; a heating sub-assembly disposed within said volume and having:aheat retention member for absorbing and retaining sensible heat and forreleasing said sensible heat over extended periods of time; a heatingcoil assembly secured to a surface of said heat retention member, saidheating coil assembly including a resistive heating coil disposed overan area substantially equal to an area of said heat retention member,said coil disposed within a sealed thermally conductive pouch; a powercord extending into said pouch with an internal end of said cord securedto said coil, an external end of said cord having means for releasableconnection to a source of electric power; said heating sub-assemblyincludes a rigid base having a surface area greater than an area of saidheating coil assembly; said heating coil assembly and heat retentionmember secured to said base with said coil assembly disposed betweensaid base and said heat retention member, said coil assembly and heatretention member covering only a portion of said base to define anuncovered portion of said base; and a thermally conductive materialextending from a location adjacent said coil assembly to cover saiduncovered portion for conducting heat from said assembly throughout saiduncovered portion.
 8. An apparatus according to claim 7 furthercomprising an interior wall within said volume for dividing said volumeinto a first sub-chamber sized to receive said article and asecond-chamber sized to receive said heating sub-assembly.
 9. Anapparatus according to claim 7 wherein:said walls include spaced apartsidewalls joined by a back wall at a trailing end and further joined bytop and bottom walls to define said interior volume, said walls furtherdefining said opening; said walls formed of thermally insulativematerial; said cover hingedly secured to an edge of one of said top andbottom walls for said cover to pivot between an open and a closedposition, said cover in said closed position covering said opening. 10.An apparatus according to claim 9 further comprising flexible side flapssecured to respective ones of said sidewalls and to said cover, saidside flaps including folds for urging said side flaps inwardly into saidopening as said cover is moved to said closed position.
 11. An apparatusaccording to claim 10 wherein said interior wall is disposed inoverlying relation to said bottom wall.
 12. An apparatus according toclaim 10 wherein one of said side flaps is releasably secured to saidcover with fastening means to permit said cord to extend between saidone of said flaps and said cover.
 13. An apparatus according to claim 7wherein said sub-assembly is disposed in said volume with said uncoveredportion positioned adjacent a trailing end of said volume.a power cordextending into said thermally conductive pouch with an internal end ofsaid cord secured to said coil, an external end of said cord havingmeans for releasable connection to a source of electric power; a rigidbase having a surface area greater than an area of said heating coilassembly; said heating coil assembly and heat retention member securedto said base with said coil assembly disposed between said base and saidheat retention member, said coil assembly and heat retention membercovering only a portion of said base to define an uncovered portion ofsaid base; and a thermally conductive material extending from a locationadjacent said heating coil assembly to cover said uncovered portion forconducting heat from said heating coil assembly throughout saiduncovered portion.
 14. An apparatus for storing a heated articleaccording to claim 7, wherein the heat retention member comprises water.15. An apparatus for storing a heated article according to claim 7,wherein the heat retention member comprises a dielectric oil.
 16. Anapparatus for storing a heated article according to claim 7, wherein theheat retention member comprises a phase change material for storage oflatent heat.
 17. An apparatus for storing a heated article according toclaim 7, wherein said heated article comprises a food product.
 18. Anapparatus for storing a heated article according to claim 17, whereinsaid food product comprises pizza.
 19. An apparatus for storing a heatedarticle according to claim 17, wherein said food product comprises aplurality of cardboard boxes each containing an individual pizza.
 20. Athermal storage assembly comprising:a thermally conductive materialhaving a top surface and a bottom surface, and comprising a heat sinkmaterial, said thermally conductive material provided for absorbing andretaining heat and for releasing heat over extended periods of time; aheating assembly comprising a resistive heating element, wherein saidheating assembly is provided in thermally conductive contact with saidthermally conductive material; a power cord extending into said heatingassembly with an internal end of said cord secured in electricallyconductive communication to said resistive heating element, an externalend of said cord having means for releasable connection to a source ofelectrical power; said thermally conductive material and said heatingassembly disposed within a sealed enclosure, wherein the sealedenclosure comprises a base having a surface area greater than a surfacearea of the bottom side of said thermally conductive material to definean uncovered portion of said base.
 21. A thermal storage assemblyaccording to claim 20, wherein said base comprises a rigid material. 22.A thermal storage assembly according to claim 20, wherein the thermallyconductive material comprises a dielectric oil.
 23. A thermal storageassembly according to claim 20, wherein the thermally conductivematerial comprises a phase change material for storage of latent heat.24. An apparatus for storing a heated article, said apparatuscomprising:a case having walls defining an interior volume sized toreceive said article, said walls further defining an opening for accessto said volume; a cover for closing said opening; a heating sub-assemblydisposed within said volume and having:a thermally conductive materialhaving a top surface and a bottom surface, and comprising a heat sinkmaterial for absorbing and retaining heat and for releasing saidsensible heat over extended periods of time; a heating assemblycomprising a resistive heating element, wherein said heating assembly isprovided in the thermally conductive contact with said thermallyconductive material; a power cord extending into said heating assemblywith an internal end of said cord secured in electrically conductivecommunication to said resistive heating element, an external end of saidcord having means for releasable connection to a source of electricpower; said thermally conductive material and said heating assemblydisposed within a sealed enclosure, wherein the sealed enclosurecomprises a base having a surface area greater than a surface area ofthe bottom side of said thermally conductive material; said heatingassembly and thermally conductive material secured to said base withsaid coil assembly disposed between said base and at least a portion ofsaid heat retention member, said coil assembly and heat retention membercovering only a portion of said base to define an uncovered portion ofsaid base.
 25. An apparatus for storing a heated article according toclaim 24, wherein said interior volume is sized to receive a pluralityof cardboard boxes each containing an individual pizza.
 26. An apparatusfor storing a heated article according to claim 24, wherein said casefurther comprises a wall including vent holes for venting moisture fromsaid interior.
 27. An apparatus for storing a heated article accordingto claim 24, wherein the thermally conductive material comprises adielectric oil.
 28. An apparatus for storing a heated article accordingto claim 24, wherein the thermally conductive material comprises a phasechange material for storage of latent heat.